Fake STK4231?

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#22
As a service technician and having significant exp in assembling many varieties of equipment right from the valv e days having multitudes as well as multi 'event' experiences with varied types of devices I can state with reasonable authority that the spare part scenery of many semicons and shockingly extending to many passive devices nowadays as well is a rather grim one. There is no reliable way of getting away with a reliable device as the clone is so much identical many of the popular power transistors test ok at the dealer, but fail miserably when inserted into 'service'. The scene has however improved marginally. I remember back in my teens we used to get fleeced by counterfeits that were totally different to what we asked for and probably a cheaply labelled digital Ic instead of a costly analog video ic for example. This practice of relabelling products has now largely come down partially because of growing awareness and partially because of large scale rebellion from users accross the spectrum esp in the media. Now coming to semis, I can state confidently that if you are purchasing then as straight replacements for servicing commercial units like hi pwr amplifiers, then you better confirm that there semi. In Q is genuine. That's because original semis that are used are usually used at close to ( but within) its power ratings.A spurious device will rarely survive here. But if you are using it to make an assembled product, then you may succeed by (usually 50-70%) derating the pwr supply as this almost always assured success with cloned devices with many of them easily passing the common MM test. The same goes for STK,s as well,( amazing pt is that the original mfr Sanyo stopped the mfg of these very successful devices leaving the field open to everyone else) that they were so successful that multitudes of clone mfg units sprang up everywhere esp in China. Point 2b noted here is China is like India, a very large country with a vast multitude of manufacturers with many of them manufacturing very gd products, but the motives of many of the others is obviously open to question. Success with these devices varies from mfr to mfr. And here I suspect that as there are many variants within the same group, The lowest pwr wattage version that is pin to pin compatible with the higher pwr and higher voltage variant within its "family" is passed off as a genuine one. Point 2b observed is that the device will work well if used in low pwr mode like if you were you install it in an assembled amp for example, but will def blow up if used as a replacement in a commercial amplifier where the pwr applied is obviously higher and 'non negotiable.' And this rule of thumb should be applied to pwr transistors as well. You will obviously succeed if you keep note of these points as well as ample caution when dealing with the sort of devices. Happy building. Take care,Bye. prashanth58@gmail.com
 
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#23
As a service technician from Mangalore, India and having significant exp in assembling many varieties of equipment right from the valve days as well as multi 'event' experiences with varied types of devices I can state with reasonable authority that the spare part scenery of many semicons and shockingly extending to many passive devices nowadays as well is a rather grim one. There is no reliable way of getting away with a reliable device as the clone is so much identical many of the popular power transistors test ok at the dealer, but fail miserably when inserted into 'service'. The scene has however improved marginally. I remember back in my teens we used to get fleeced by counterfeits that were totally different to what we asked for and probably a cheaply labelled digital Ic instead of a costly analog video ic for example. This practice of relabelling products has now largely come down partially because of growing awareness and partially because of large scale rebellion from users accross the spectrum esp in the media. Now coming to semis, I can state confidently that if you are purchasing then as straight replacements for servicing commercial units like hi pwr amplifiers, then you better confirm that there semi. In Q is genuine. That's because original semis that are used are usually used at close to ( but within) its power ratings.A spurious device will rarely survive here. But if you are using it to make an assembled product, then you may succeed by (usually 50-70%) derating the pwr supply as this almost always assured success with cloned devices with many of them easily passing the common MM test. The same goes for STK,s as well,( amazing pt is that the original mfr Sanyo stopped the mfg of these very successful devices leaving the field open to everyone else) that they were so successful that multitudes of clone mfg units sprang up everywhere esp in China. Point 2b noted here is China is like India, a very large country with a vast multitude of manufacturers with many of them manufacturing very gd products, but the motives of many of the others is obviously open to question. Success with these devices varies from mfr to mfr. And here I suspect that as there are many variants within the same group, The lowest pwr wattage version that is pin to pin compatible with the higher pwr and higher voltage variant within its "family" is passed off as a genuine one. Point 2b observed is that the device will work well if used in low pwr mode like if you were you install it in an assembled amp for example, but will def blow up if used as a replacement in a commercial amplifier where the pwr applied is obviously higher and 'non negotiable.' And this rule of thumb should be applied to pwr transistors as well. You will obviously succeed if you keep note of these points as well as ample caution when dealing with the sort of devices. Happy building. Take care,Bye. prashanth58@gmail.com
 
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